South Florida May Rainfall Watch (Lushine Dry May Theory)

[gatorcane]

NWS Miami extended forecast backs off on rain chances, so the extremely dry May continues for Southern Florida even going into the second half of May where we would expect higher rain chances than just less than 20%.

.EXTENDED FORECAST...
THE MID TO UPPER LEVEL HIGH WILL REBUILD OVER THE FLORIDA KEYS NEXT WEEK....AS A SURFACE HIGH BUILDS EAST OF THE BAHAMA ISLANDS. THIS WILL ALLOW FOR THE WINDS OVER THE CWA TO SWING FROM A SOUTHWEST DIRECTION EARLY NEXT WEEK TO A SOUTHERLY DIRECTION BY THE END OF NEXT WEEK. AT THE SAME TIME...THE ATMOSPHERE OVER SOUTH FLORIDA WILL ALSO BECOME STABLE AS THE WEEK PROGRESS. SO WILL KEEP A SLIGHT CHANCE OF SHOWERS IN THE FORECAST FOR NEXT WEEK...BUT THE POPS WILL BE 20 PERCENT OR LESS OVER THE AREA FOR NEXT WEEK.

Miami International: MONTH TO DATE 0.05
Ft. Lauderdale International: MONTH TO DATE 0.02
West Palm Beach International: MONTH TO DATE 0.24

[Rainband]

coincidence nothing more....

[Nimbus]

You see this all the time in sports, its like a team with good stats that gets jinxed playing in a certain city. Its probably a statistical illusion that takes on more weight than it should.

If we have a record dry May in South Florida this year, the jinx could be broken with early season tropical activity. In the years with driest Mays historically it was not till mid August that the major hurricanes threatened Florida.

[Sanibel]

We usually have a few thunderstorms by the end of May as the sun heats the land so much that it forces convection. We have this weird SW flow over us with mild maritime air.

[Blown Away]

SFL is on pace to have one of the driest May's on record. The second half of May is usually when we start to see our typical summer rainfall pattern. I'm still waiting for our first afternoon thunderstorm, temperatures are mild for May so far.

[boca]

Traditionally rainy season starts May 21st. The way the pattern is I don't see us getting rain until the second week in June.When is the latest start date for rainy season? I think that date might be in jepardy.

[gatorcane]

Hi Boca, the latest start to the South Florida rainy season on record (based on 42 years of records) is June 3rd of of 1971. That year did not produce a direct hit on South Florida but two strong tropical storms came very close and Doria turned and hit the Carolinas instead AND although the rainy season did not start until June 3rd, it was not the driest May.

But, the three driest Mays for South Florida on record produced direct hits for South Florida by major hurricanes. These include Andrew, 1935 Keys Hurricane, and Betsy.

Coincidence or not? The verdict is still out.

Here is the link:
http://www.srh.noaa.gov/mfl/newpage/summer_season.html

[BocaGirl]

But, the three driest Mays for South Florida on record produced direct hits for South Florida by major hurricanes. These include Andrew, 1935 Keys Hurricane, and Betsy.

Coincidence or not? The verdict is still out.

I'm coming to the thread late, so please forgive me if my question has already been answered.....

What about wet Mays? How many storms hit South Florida in years in which the month of May was wet? It might be interesting to see the reverse statistic before drawing a conclusion.

BocaGirl
Barbara

[Blown Away]

Read the article and then you will understand the discussion.

http://www.insurancejournal.com/news/so ... /54367.htm

[JPmia]

Read the article and then you will understand the discussion.

http://www.insurancejournal.com/news/so ... /54367.htm

so did Lushine move to Alaska? I imagine he didn't considering what happened a couple of months later to South Florida that season in 2005. As far as dryness is concerned, we are definitely DRY down here. Lower humidities and hot dry breezy air..this May reminds of 1992, 1999, 2004 when we were very dry.

[gatorcane]

But, the three driest Mays for South Florida on record produced direct hits for South Florida by major hurricanes. These include Andrew, 1935 Keys Hurricane, and Betsy.

Coincidence or not? The verdict is still out.

I'm coming to the thread late, so please forgive me if my question has already been answered.....

What about wet Mays? How many storms hit South Florida in years in which the month of May was wet? It might be interesting to see the reverse statistic before drawing a conclusion.

BocaGirl
Barbara

Barbara, that's a good question. In fact supposely 1947 and 1949 were very wet years for SE Florida when Palm Beach County saw direct hits from Cape Verde major hurricanes.

I would like to see what the rain totals were for May of those years because I am having a hard time finding this information.

Does anybody have May rainfall totals for those years?

[MiamiensisWx]

Gator, here's an excellent site for historical precipitation data from numerous statewide stations, including south Florida localities. Save it for future reference.

http://www.coaps.fsu.edu/climate_center/nav.php?a=go&s=data&p=prcpdat

Miami, FL data extends to 1900, while West Palm Beach extends to 1890. Average May rainfall for Miami is 5.52 inches (http://www.srh.noaa.gov/mfl/newpage/climate/Miami_May_Climat.html), while the average May precipitation is 5.39 inches at West Palm Beach (http://www.srh.noaa.gov/mfl/newpage/climate/Palm-Beach_May_Climat.html). The data reveals there have been several dry Mays at MIA/WPB during +AMO (active Atlantic) regimes that featured no TC strikes in southern Florida, including 1927, 1955, 1995 (Erin made landfall north of south FL), 2000, and others. I have also found several near average, average, or above average Mays that featured TC strikes, including 1916 (TS), 1919 (Cat 4), 1924 (Cat 1), 1929 (Cat 3), 1944 (Cat 3), 1947 (Cat 4 and 1), 1949 (Cat 3), 1964 (two Cat 2 systems), 1966 (Cat 1), and 2005 (Cat 1 and 3). Although you can also find several dry Mays with strikes, it is important to note that May is the second driest month in Florida and south FL; April is the state's driest month. Most of May typically features scarce precipitation, though a gradual increase in rainfall often occurs toward the very end of the month as the rainy season commences. In fact, most "wet Mays" received the vast majority of rainfall toward the last week of the month; otherwise, the month was largely typically dry.

In a nutshell, although the "big three" years of 1935, 1965, and 1992 (driest Mays recorded) stand out with the "big three" strikes (Cat 3 and two Cat 5 hits), they were likely coincidences based on this expansive overview of the data. May is simply a very dry month in the state in most cases, so it is very hard to discern any miniscule patterns that occurred in a handful of cases out of a vast climatological database.

By the way, May 1947 featured 5.44 inches at MIA and 10.11 inches at WPB; May 1949 featured 5 inches at WPB and 6.07 inches at MIA. Overall, precipitation was above average across south FL.

[Patrick99]

I don't know - it may seem like we are not going to get any rain until mid-June, but when the season switches on, it really switches on, and it doesn't take all that much. Without more freak dry-frontal passages sweeping things clean, hot and dry, the afternoon thunderstorms will get going, for someone.

Before this last front came through, it seemed to me as though rainy season had a chance of getting going early.

[Sanibel]

We usually get a wall of convection building over the mainland by now, not a cloud so far. The humidity is back starting tomorrow (right on time).

[Blown Away]

Hi Boca, the latest start to the South Florida rainy season on record (based on 42 years of records) is June 3rd of of 1971. That year did not produce a direct hit on South Florida but two strong tropical storms came very close and Doria turned and hit the Carolinas instead AND although the rainy season did not start until June 3rd, it was not the driest May.

But, the three driest Mays for South Florida on record produced direct hits for South Florida by major hurricanes. These include Andrew, 1935 Keys Hurricane, and Betsy.

Coincidence or not? The verdict is still out.

Here is the link:
http://www.srh.noaa.gov/mfl/newpage/summer_season.html

How's this formula: Late beginning to the SFL wet season (@ May 28th) + < 2" of SFL May rainfall = Very high chance of a hurricane for SFL.

[MiamiensisWx]

Gator, here's an excellent site for historical precipitation data from numerous statewide stations, including south Florida localities. Save it for future reference.

http://www.coaps.fsu.edu/climate_center/nav.php?a=go&s=data&p=prcpdat

Miami, FL data extends to 1900, while West Palm Beach extends to 1890. Average May rainfall for Miami is 5.52 inches (http://www.srh.noaa.gov/mfl/newpage/climate/Miami_May_Climat.html), while the average May precipitation is 5.39 inches at West Palm Beach (http://www.srh.noaa.gov/mfl/newpage/climate/Palm-Beach_May_Climat.html). The data reveals there have been several dry Mays at MIA/WPB during +AMO (active Atlantic) regimes that featured no TC strikes in southern Florida, including 1927, 1955, 1995 (Erin made landfall north of south FL), 2000, and others. I have also found several near average, average, or above average Mays that featured TC strikes, including 1916 (TS), 1919 (Cat 4), 1924 (Cat 1), 1929 (Cat 3), 1944 (Cat 3), 1947 (Cat 4 and 1), 1949 (Cat 3), 1964 (two Cat 2 systems), 1966 (Cat 1), and 2005 (Cat 1 and 3). Although you can also find several dry Mays with strikes, it is important to note that May is the second driest month in Florida and south FL; April is the state's driest month. Most of May typically features scarce precipitation, though a gradual increase in rainfall often occurs toward the very end of the month as the rainy season commences. In fact, most "wet Mays" received the vast majority of rainfall toward the last week of the month; otherwise, the month was largely typically dry.

In a nutshell, although the "big three" years of 1935, 1965, and 1992 (driest Mays recorded) stand out with the "big three" strikes (Cat 3 and two Cat 5 hits), they were likely coincidences based on this expansive overview of the data. May is simply a very dry month in the state in most cases, so it is very hard to discern any miniscule patterns that occurred in a handful of cases out of a vast climatological database.

By the way, May 1947 featured 5.44 inches at MIA and 10.11 inches at WPB; May 1949 featured 5 inches at WPB and 6.07 inches at MIA. Overall, precipitation was above average across south FL.

I think this debunks the theory to a point; it does illustrate (at least) that wet Mays do not necessarily decrease the probabilities of a Cape Verde hit. The data supports my conclusion that the dry May theory is inconclusive and likely false or fluid, in my view.

What do you think, Gator, Blown, et al?

[Blown Away]

Miami, good research, I agree this theory has holes, however there seems some relationship between below average SFL May rainfall and a late start to the SFL wet season, I define a late wet season start being @28th instead of the 21st. The average May rainfall for SFL is @5.5". I'm going to need help filling some of the data.
Year/Wet Season Start Date/May Rainfall Total/Hurricane:
2005 / ??? / 4.73" / Katrina & Wilma
2004 / ??? / 1.41" / Frances & Jeanne
1999 / ??? / 4.18" / Irene
1992 / June 1 / .9" / Andrew
1985 / May 30 / ??? / Kate
1979 / May 28 / ??? / David
1966 / May 21 / ??? / Inez
1965 / May 29 / .6" / Betsy
1964 / May 12 / ??? / Cleo
1960 / May 19 / ??? / Donna

[MiamiensisWx]

Where did you find the start date and overall May precip data across southern FL? Precip data is only available for two stations (Miami and West Palm Beach). Please post a link.

[MiamiensisWx]

000
FXUS62 KMFL 172010
AFDMFL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
410 PM EDT SAT MAY 17 2008

...DRY PATTERN TO CONTINUE...
...RECORD HIGH TEMPS POSSIBLE EAST COAST AGAIN ON SUNDAY...

.DISCUSSION...PRIMARY FORECAST CONCERNS ARE DENSE SMOKE POTENTIAL
AND FIRE WEATHER CONCERNS. RADARS SHOW 2 FIRES CONTINUING...ONE
OVER SW LAKE OKEECHOBEE AND THE OTHER OVER THE EVERGLADES. KAMX
REALLY SHOWS THE FIRE WELL WITH THE HIGHER REFLECTIVITIES MOVING
OVER KROME AVE. MAINLY SOUTH OF TAMIAMI TRAIL. KTMB VIS HAS BEEN
FALLING ALL AFTERNOON AND IS NOW DOWN TO 2SM. NO LUCK WITH CALLS
TO SEE WHAT THE VISIBILITY IS RIGHT NOW ALONG KROME AVE...BUT IT
LIKELY IS LESS THAN A MILE AND COULD EVEN BE DOWN TO A QUARTER OF
A MILE IN DENSE SMOKE. THE PATTERN TONIGHT FAVORS SMOKE CONTINUING
ACROSS BROWARD/MIAMI-DADE COUNTIES...AND BECOMING DENSE ESPECIALLY
OVER INLAND AREAS AND THE WESTERN SUBURBS OF THE FT. LAUDERDALE
AND MIAMI METRO AREAS. AS SUCH...PUT UP A DENSE SMOKE ADVISORY FOR
THESE LOCATIONS. DECIDED TO START IT RIGHT NOW AS VISIBILITY IS
UNKNOWN ALONG KROME...BUT KAMX REFLECTIVITY DATA AND KTMB OB
SUGGESTS THAT DENSE SMOKE IS POSSIBLY OCCURRING THERE RIGHT NOW
EVEN DESPITE THE DAYTIME MIXING. THEREFORE...MADE THE DENSE SMOKE
ADVISORY EFFECTIVE IMMEDIATELY...AND CONTINUING THROUGH 10 AM EDT
SUNDAY. FURTHER NORTH...THE FIRE CONTINUES ON THE SW SIDE OF LAKE
OKEECHOBEE. KPBI RADAR SHOWS THE SMOKE PLUME MOVING ALMOST DUE
EAST WITH PATCHY SMOKE LIKELY AFFECTING WESTERN PALM BEACH COUNTY.
WINDS WILL BECOME LIGHT/VARIABLE ACROSS THE LAKE AREA
OVERNIGHT...AND SO DENSE SMOKE IN PATCHES IS POSSIBLE ALONG ANY
PORTION OF THE LAKESHORE ACROSS GLADES...HENDRY...AND PALM BEACH
COUNTIES OVERNIGHT. THEREFORE...TO GET THE WORD OUT ISSUED THE
DENSE SMOKE ADVISORY BUT NOT EFFECTIVE UNTIL 11 PM EDT TONIGHT.

FOR THE REST OF THE WEATHER...DRY WEATHER CONDITIONS CONTINUE
ACROSS MAINLAND SOUTH FLORIDA THIS AFTERNOON. TEMPERATURES HAVE
SOARED INTO THE 90S EAST COAST WITH MIA BREAKING THE RECORD MAX
TEMP FOR THIS DATE...REACHING 94 DEGREES (PREVIOUS RECORD WAS 93
IN 1985).

WEAK FRONTAL BOUNDARY SAGGING INTO CENTRAL FL WILL STALL THERE BUT
WILL GET A PUSH SOUTHWARD INTO THE AREA BY MONDAY...WHAT IS LEFT
OF IT...AS A SHORTWAVE KICKS OUT FROM TX. IN THE MEANTIME...DRY
WEATHER WILL CONTINUE WITH HOT TEMPS EAST COAST. A FEW RECORD
HIGHS ARE AGAIN POSSIBLE TOMORROW.

BEST CHANCE OF ANY RAIN IS ON MONDAY...BUT FORECAST SOUNDINGS
CONTINUE TO SHOW RATHER DRY AIR IN THE LOW LEVELS...SO AM NOT
VERY OPTIMISTIC ABOUT THE HIGHER GFS/NAM POPS. THUS...AM SLIGHTLY
LOWER FOR MONDAY. THE REST OF THE WEEK LOOKS DRY AS RIDGING
BUILDS IN...SO NO BENEFICIAL RAINFALL IS SEEN IN THE NEAR FUTURE.
IT SURE HAS BEEN DRY RECENTLY. HERE ARE THE RAIN STATS SINCE APRIL
10TH AT SELECTED SITES:

PBI...35" FLL...14" MIA....35" APF....07"


&&

.AVIATION...PATCHY SMOKE WITH VISIBILITIES OF A
QUARTER OF A MILE OR LESS AT TIMES IN THE EARLY MORNING NEAR LAKE
OKEECHOBEE.

&&

.MARINE...NO HEADLINES NEEDED AS WINDS WILL PREVAIL AT LESS THAN
15 KT WITH SEAS OF LESS THAN 4 FT THROUGH THE FCST PERIOD.

&&

.FIRE WEATHER...RH`S HAVE DROPPED BELOW 35 PERCENT AT A FEW EAST
COAST SITES...WITH THE LOWEST RIGHT NOW AT FT. LAUDERDALE WHERE
IT IS 94/58...WITH AN RH OF 30 PERCENT. ALL OTHER SITES ARE ABOVE
CRITICAL LEVELS. A SIMILAR PATTERN IS IN PLACE FOR TOMORROW. I
USED THE NAM12 DEWPOINTS...EVEN TRENDING SLIGHTLY LOWER AS VERY
STRONG HEATING SHOULD AGAIN LOWER DEWPOINTS SIGNIFICANTLY LOWER
THAN GFS/NAMMOS. THIS PUTS RH`S IN THE 35-40 PERCENT RANGE EASTERN
AREAS ON SUNDAY ALONG WITH WINDS HIGHER BY A FEW MPH. SO ALTHOUGH
RED FLAG CRITERIA IS NOT FORECASTED RIGHT NOW...IT LOOKS VERY
CLOSE SO THIS WILL NEED TO BE MONITORED. DRY WEATHER LOOKS TO
PREVAIL THIS UPCOMING WEEK...SO NO WIDESPREAD BENEFICIAL RAINFALL
IS IN SIGHT.

&&

.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 72 94 72 92 / 10 10 10 30
FORT LAUDERDALE 74 95 75 94 / - - 10 20
MIAMI 76 95 75 94 / - - 10 20
NAPLES 74 86 75 86 / - 10 10 30

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...DENSE SMOKE ADVISORY UNTIL 10 AM EDT SUNDAY FOR FLZ071-FLZ072-
FLZ073-FLZ074.

DENSE SMOKE ADVISORY FROM 11 PM THIS EVENING TO 10 AM EDT SUNDAY
FOR FLZ063-FLZ066-FLZ067.

AM...NONE.
GM...NONE.
&&

$$

DISCUSSION/MARINE/FIRE WEATHER...57/DG
AVIATION...04/AT

[Blown Away]

Where did you find the start date and overall May precip data across southern FL? Precip data is only available for two stations (Miami and West Palm Beach). Please post a link.

Data from SFWMD for Miami/Dade:
https://my.sfwmd.gov/portal/page?_pagei ... ema=PORTAL